Trip device for use in a feed mechanism of a machine

ABSTRACT

In the quill feed mechanism of a milling machine, a trip device which disconnects the drive if the quill meets an unyielding obstruction, comprising a pivoted housing carrying a gear which forms part of the feed mechanism, an angled face clutch and a latch mechanism arranged so that when an abnormal torque is imposed on the said gear, the latch mechanism disengages so that the housing pivots to disconnect the feed drive.

United States Patent [191 Firth 1 Jan. 29, 1974 TRIP DEVICE FOR USE IN A FEED MECHANISM OF A MACHINE [75] Inventor: Arthur Jose Firth, Colchester,

England [73] Assignee: 600 Machine Tools Limited, 8 London, England 22 Filed: Feb. 22, 1972 21 Appl. No.2 227,805 1 [30] Foreign Application Priority Data Feb. 25, 1971 7 Great Britain 5431/71 7 [52] US. Cl 74/412 TL, 74/405, 192/56 R [51] Int. Cl. Fl6d 7/02 [58] Field of Search 74/405, 412 TL, 380; 408/133; 192/56 R, 56 L [56] References Cited UNITED STATES PATENTS 2,885,901 5/1959 Firth .f. 74/405 229,993 7/1880 Flenniken 74/405 I 1,250,362 12/1917 Schellenbach 408/133 1,760,430 5/1930 Mirrielees 408/133 X Primary Examiner-Benjamin W. Wyche Assistant Examiner-Allan Russell Burke Attorney, Agent, orFirm-Bacon & Thomas [5 7] ABSTRACT In the quill feed mechanism of a milling machine, a trip device which disconnects the drive if the quill meets an unyielding obstruction, comprising a pivoted housing carrying a gear which forms part of the feed mechanism, an angled face clutch and a latch mechanism arranged so that when an abnormal torque is imposed on the said gear, the latch mechanism disengages so that the housing pivots, to disconnect the feed drive. t

7 Claims, 4 Drawing Figures TRIP DEVICE FOR USE IN A FEED MECHANISM OF A MACHINE This invention relates to a trip device for use in a feed mechanism of a machine and particularly to such a device in the quill feed mechanism of a milling machine.

. Numerous machines, particularly machine tools, are fitted with trip devices to prevent undue strain and stress being imposed on a part. In milling machines, trip devices are present in the quill feed mechanism so that if the milling cutter or the quill meets an unyielding obstruction, either in its forward or-reverse feed, the feed will be arrested until the operator removes the obstruction. y

It is the main object of this invention to provide a trip device for use in the quill feed mechanism of a milling machine which is simple in construction and positive in its operation. 1

According to the present invention there is provided a trip device for use in a feed mechanism ofa machine, including a gear forming part of the feed mechanism, a pivotal housing carrying the said gear, an angled face clutch through which torque is transmitted for the feed; and a latch mechanism comprising a pin carried by the housing and axially movable by the clutch when an abnormal torque is imposed on the said gear, said axial movement disengaging the pin'from an arm, whereby the pin and gear move with the housing under spring action to disengage the feed mechanism, said movement causing a cam track on the housing to move the arm to a second position.

The invention also includes a trip device as aforesaid, in which the pin is spring loaded to a stop position with the clutch fully engaged. A manually operable lever or wheel may be fixed to the said arm for resetting the trip device.

In order more particularly to describe the invention, one embodiment thereof will now be described, by way of example only. and with reference to the accompanying drawing, in which:

FIG. 1 is a diagrammatic perspective view of a quill feed drive mechanism for a milling machine incorporating a trip device according to the invention;

H6. 2 is a diagrammatic plan view of the forward and reverse drive mechanism of FIG. 1;

HO. 3 is a diagrammatic plan view of an alternative forward and reverse drive mechanism; and

HO. 4 is a diagrammatic perspective view showing further parts of the trip device of FIG. 1.

ln the drawing, there is shown a drive shaft 1 carrying a worm 2 The drive shaft 1 and worm 2 are driven from a prime mover in known manner. A driven shaft 3 carries a spiral gear 4 and this driven shaft 3 drives further mechanism for feeding the'quill which forms no part of the present invention. A housing 5, see FIG. 2, is pivotally mounted for rotation about the driven shaft 3 and the housing 5 is manually movable by a lever 6 attached to a shaft 7 having a pin 8 which engages the housing 5. The lever 6 may be replaced by a hand wheel. The housing 5 carries a forward feed lay shaft 9 and a reverse feed lay shaft 10 lying one on each side ofthe worm 2. The lay shafts 9 and 10 are disposed parallel to each other and carry worm wheels 11 and 12 respectively for selective engagement with worm 2 on operation of lever 6. Lay shaft 9 carries a spiral pinion 13 in engagement with spiral gear 4 and also a spur gear 14 meshing with idler spur gear 15 which, in turn, meshes with spur gear 16 on lay shaft 10. Idler spur wheels 28 or 29 meshing with worm 22.

lever 6 is manually operable to move the housing 5 to one of three selectable positions. Each such. position may be temporarily retained-by a detent mechanism (not shown) and the position of the lever 6 will indicate to the operator of the machine in which positionthe feed mechanism is presently situated. If a hand wheel replaces the lever 6, the hand wheel will be provided with a suitable indicating means to show the state of the mechanism.

In use, if the lever 6 is moved to the position 18, the housing 5 will be pivoted 'about driven shaft 3 so that worm wheel 11 engages worth 2 and the driven shaft 3 will be rotated in a sense for the forward feed of the quill. If the lever 6 is moved to the position 19 worm wheel 12 engages worm 2 and driven shaft 3 will be totated in the reverse sense for reverse feed of the quill. If, however, lever 6 is moved to the position 20 as indicated in the drawing, neither of worm wheels 11 or 12 will be engaged with worm 2 and the feed drive will be. disconnected.

An alternative embodiment of forward and reverse drive mechanism in accordance with the invention is shown in FIG. 3. In this embodiment, a drive shaft 21 carries a worm 22, driven, as in the previous embodiment, by a prime mover (not shown). A driven shaft'23 carries a bevel gear wheel 24 and a housing 25 is pivotally mounted for movement about shaft 23. The housing 25 carries a forward drive layshaft 26 and a reverse drive lay shaft 27 both disposed radially with respect to the bevel gear wheel 24.and lying one on each side of the worm 22. The lay, shafts 26 and 27 carry worm wheels 28 and 29 respectively for selective engagement. with worm 22 and also carry bevel gears 30.and 31 re-, spectively meshing with bevel gear wheel 24.

The housing 25 is manually movableby a lever or hand wheel (not shown) mountedon shaft 32 having a pin 33 which engages the housing '25. ln this embodiment also, detent means may be provided for temporarily retaining the lever orhandwheel in one of three selectable positions, namely, for forward feed with the worm wheel 28 meshing with worm 22; for reverse feed with the worm wheel 29 meshing with worm 22; or for disengagement of the feed with neither of the worm Driven shaft 3 carries three spur gears 34, 35 and 36 of a speed change gear assembly and these three gears selectively engage spur gears 37, 38 and 39 respectively carried by intermediate drive shaft 40. The three gears 37, 38 and 39 are manually-movable by fork 41 pivotally mounted on crank 42hand operable by lever 43 turning shaft 44. Lever 43 may be replaced by a hand wheel. Lever 43 has three positions for engagement of the gear pairs and also'two further positions which may lie between the three gear enga'gement positions. These two further positions'are neutral positions, indicating that all the gears are disengaged.

Intermediate drive shaft 40 carries a helical or spiral gear 45 which meshes with a similar gear 46 on shaft 47 turned by hand wheel 48 for effecting fine feed, either forward or reverse, of the quill. This hand wheel 48 may be provided with a disengagement means (not shown) which would only be engaged when fine hand feed of the quill is to be effected.

The intermediate drive shaft 40 has, freely rotatable thereon, a spur gear 49. This gear 49, however, is prevented from movement axially of the intermediate shaft 40. Forming part of gear 49 is a first angled face clutch part 50 co-operating with a second angled face clutch part 51 splined to intermediate shaft 40 for rotation therewith and for axial movement thereon and loaded by spring 52 to the engaged position. Clutch part 51 has below it flange 53 integral with boss 54 which carries pin 55 having a flat 56, the boss 54 being loaded by spring 57. The lower end of pin 55 enters a further housing 58 more particularly shown in FIG. 4 and this further housing 58 carries a shaft 59 on which is mounted a worm 60 and a spur gear 61, the latter meshing with spur gear 49.

The further housing 58 is pivotally mounted about intermediate shaft 40 and, in the position of further housing 58 shown in the drawing, worm 60 is in engagement with a worm wheel 62 carried by an output shaft 63 having a pinion 64 for engagement with a rack (not shown) attached to the quill.

The further housing 58 is loaded by spring 65 tending to pivot further housing 58 about intermediate shaft 40 and disengage worm 60 from worm wheel 62 but, under normal quill feed conditions, this is prevented by an arm 66 having a part 67 thereof being engaged by the pin 55. This arm 66 is spaced from the housing 58 and is pivotally mounted intermediate its ends on a fixed part of the machine and has a wheel 68 engaging a cam track 69 forming part of the further housing 58. A shaft 70 rotatably mounted in a fixed part of the machine. is rigid with the arm 66 and connects a lever or hand wheel 71 to the arm 66 for pivoting the arm 66 and moving the wheel 68 along the cam track 69 for manual engagement and disengagement of worm 60 and worm wheel 62. Obviously the shaft 70 is held against axial movement.

In operation and during normal forward or reverse feed of the quill, intermediate shaft 40 will turn clutch part 51 which. is splined to it and through the angled faces of'the clutch will drive gear 49, gear 61 and shaft 59. This will drive worm 60, worm wheel 62, shaft 63 and pinion 64 to feed the quill. If, however, any abnormal torque is imposed on worm 60 due to the quill or tool meeting an unyielding obstruction, rotation of spur gear.49 will be curtailed and the clutch angled faces will ride up. This will cause clutch part 51 and flange 53 to move downwardly carrying pin 55 downwardly until pin 55 is free of the restraint of arm 66, whereupon spring 65 will cause pivotal movement of further housing 58 and disengagement of worm 60 from worm wheel 62. This pivotal movement causes wheel 68 to ride along cam track 69 thus pivoting arm 66 to its second position with part 67 raised. Rotation of lever or hand wheel 71 clockwise (as seen in the drawing) will reset the trip device and reengage worm 60 with worm wheel 62 for further feed of the quill.

The output shaft 63 may be manually operated by a lever'72 for effecting coarse feed of the quill and disengagement means (not shown) may be associated with this coarse feed lever so that the lever will only become operable when coarse feed is to be effected.

in a' milling machine having the above mechanism, an

operator having set up his tooling and workpiece on the machine and desiring to use power feed, would first select the feed direction required by movement of lever 6. Second, he would select the desired rate of feed by movement of lever 43. Then with the tool rotating, he would bring the tool to the workpiece by movement of the coarse feed lever 72.

The operator will then either set a depth stop on the machine and engage power feed by lever 71, or, if the travel is to be unrestricted, simply move the lever 71 to the engaged position. The trip mechanism will disconnect the feed when the depth stop is reached, when the tool encounters an unyielding obstruction or when the operator moves the lever 71 to the disengaged position.

Should the operator require the use of the fine feed handwheel 48, he would move either, or both, the lever 43 or lever 6 to a neutral position and engage lever 71. The trip mechanism functions in the normal manner for overload or depth setting. V

The assembly described above, while eminently suitable for use in a milling machine has other applications in machines where several facilities are desirable.

I claim:

1. in a trip device for use in a feed mechanism of a machine, the improvement comprising:

a feed mechanism having a gear through which drive is transmitted, a housing carrying the said gear, said housing having a cam track thereon.

a pivotal mounting means for the said housing, an angled face clutch through which torque is transmitted for the said feed mechanism operably connected with said gear, and a latch mechanism, comprising a pin carried by the housing, said pin being axially movable by the said clutch when an. abnormal torque isimposed on the said gear, and a movable arm in contact with said cam track and engageable, in a first position, by the said pin for maintaining said gear engaged with the feed mechanism, said arm being movable to a second position by the ac.- tion of said cam track when the said pin is disengaged from the said arm thereby permitting the housing to pivot and disengage the said gear from the feed mechanism.

2. In a trip device as defined in claim 1, the improvement further comprising a spring loading the said pin to a stop position when the said clutch is fully engaged.

3. In a trip device as defined in claim 2, the improvement further comprising I a manually operable means fixed to the said arm for resetting the said trip device.

4. A trip device for use in a feeding mechanism of machine, comprising: a drive shaft;

a driven shaft; first gear means rigid with said driven shaft; I

a housing disposed adjacent said driven shaft;-

a rotatable intermediate shaft carried by said housing;

second gear means rigid with said intermediate shaft;

means for transmitting rotary movement of said drive shaft to said intermediate shaft including normally engaged clutch means;

means mounting said housing for pivotal movement between a first position with the second gear means in operative engagement with-the first gear means and a second position with the second gear means out of operative engagement with the first gear means;

means biasing said housing toward said second position;

a cam track rigid with said housing;

a latch member movable between first and second positions and having a cam track follower in enbetween a latched position holding said latch member in its first position and an unlatched position permitting said latch member to move to its second position; and

means responsive to a predetermined abnormal torque encountered by said driven shaft for disengaging said clutch means and moving said latch means to its unlatched position.

5. A trip device according to claim 4, including manual means connected with said latch member for moving it from its second to its first position.

6. A trip device according to claim 4 in which said clutch means comprises a drive member splined to said drive shaft and a driven member freely rotatable on said drive shaft, said driven member having a gear rigid therewith and in driving engagement with said second gear means.

7. A trip device according to .claim 4 in which said housing is mounted on said drive shaft for its pivotal movement. 

1. In a trip device for use in a feed mechanism of a machine, the improvement comprising: a feed mechanism having a gear through which drive is transmitted, a housing carrying the said gear, said housing having a cam track thereon, a pivotal mounting means for the said housing, an angled face clutch through which torque is transmitted for the said feed mechanism operably connected with said gear, and a latch mechanism, comprising a pin carried by the housing, said pin being axially movable by the said clutch when an abnormal torque is imposed on the said gear, and a movable arm in contact with said cam track and engageable, in a first position, by the said pin for maintaining said gear engaged with the feed mechanism, said arm being movable to a second position by the action of said cam track when the said pin is disengaged from the said arm thereby permitting the housing to pivot and disengage the said gear from the feed mechanism.
 2. In a trip device as defined in claim 1, the improvement further comprising a spring loading the said pin to a stop position when the said clutch is fully engaged.
 3. In a trip device as defined in claim 2, the improvement further comprising a manually operable means fixed to the said arm for resetting the said trip device.
 4. A trip device for use in a feeding mechanism of a machine, comprising: a drive shaft; a driven shaft; first gear means rigid with said driven shaft; a housing disposed adjacent said driven shaft; a rotatable intermediate shaft carried by said housing; second gear means rigid with said intermediate shaft; means for transmitting rotary movement of said drive shaft to said intermediate shaft including normally engaged clutch means; means mounting said housing for pivotal movement between a first position with the second gear means in operative engagement with the first gear means and a second position with the second gear means out of operative engagement with the first gear means; means biasing said housing toward said second position; a cam track rigid with said housing; a latch member movable between first and second positions and having a cam track follower in engagement with said cam track, said latch member, when in said first position, holding said housing in its first position and when in its second position, permitting said housing to pivot to its second position; latch means operatively connected with said clutch means and with said latch member and movable between a latched position holding said latch member in its first position and an unlatched position permitting said latch member to move to its second position; and means responsive to a predetermined abnormal torque encountered by said driven shaft for disengaging said clutch means and moving said latch means to its unlatched position.
 5. A trip device according to claim 4, including manual means connected with said latch member for moving it from its second to its first position.
 6. A trip device according to claim 4 in which said clutch means comprises a drive member splined to said drive shaft and a driven member freely rotatable on said drive shaft, said driven member having a gear rigid therewith and in driving engagement with said second gear means.
 7. A trip device according to claim 4 in which said housing is mounted on said drive shaft for its pivotal movement. 